The present invention relates to a coating composition for protecting the bodies of automobiles or the like and at the same time displaying a soft and unique texture by way of ornament.
For a finish coating of automobiles and bicycles, a method of using a solid color coating and a method of using a metallic coating are mainly adopted.
Inorganic pigments such as titanium dioxide pigments and iron oxide pigments, and organic pigments having excellent weather resistance such as copper phthalocyanine pigments, quinacridone pigments and perylene pigments are usually used for a solid color coating.
For metallic coating, metal powder such as aluminum powder and mica are used together with the above-described organic pigments or the like so as to display a unique texture.
A coating film formed by using such a metallic coating is required to have a sufficient durability for protecting the substrate and an ornamental property (beautiful appearance).
More particularly, there is a strong demand for diversification of coating film such as coating color and ornamental property (beautiful appearance) of top coat, in order to satisfy a current trend toward individuality In particular, there is a strong demand for coating compositions which can form coating films capable of giving a variety to the unique texture of the coating film.
Iron oxide particles which are typical coloring pigment, have been used in particle shapes such as granular form, spindle-like form, plate-like form and the like.
In particular, various attempts have been conducted for plate-like ion oxide particles as a component of coating composition, since the plate-like oxide particles exhibit gloss (refer to Japanese Patent Publication Nos. 63-41853 (1988), 60-8977 (1985) and 3-52413(1991), Japanese Patent Application Laid-Open (KOKAI) No. 61-174120 (1986).
Although a coating composition which meets a demand for deversification of the coating film, such as the coating color and the ornamental property, and in particular, gives a variety to the unique texture of the coating film is strongly demanded, the coating compositions containing the above-mentioned iron oxide particles could not satisfactorily meet these demands. Therefore, coloring pigments having a high degree of transparency (low hiding power), such as a transparent iron oxide pigment, the copper phthalocyanine pigment, the quinacridone pigment and the perylene pigment are used, both in the cases of solid color coating and metallic coating. In these cases, however, there is a problem in that the hiding power of the coating film is reduced. In order to improved the hiding power of this coating film, various attempts have been conducted, such as enhancement of concentration of pigment in the coating film, thickening of the coating film and combined use with a pigment having as high hiding power. These attempts, however, are not said to be satisfied and preferred from the view point of properties of coating film. In particular, the combined use with the pigment having high hiding power has brought about a new problem of turbidity of hues.
Accordingly, it is required to provide a coating composition which can meet the demand for diversification of coating film such as a coating color and an ornamental property and can give a variety to the unique texture of the coating film, and which can form a coating film having an excellent hiding power and being suppressed turbidity of hues.
As a result of the present inventors' study, it has been found that by applying on a base plate a coating composition obtained by mixing plate-like iron oxide particles having an average particle diameter (lamellar diameter) of 4 to 25 .mu.m, a lamellar thickness of 0.16 to 5 .mu.m and a plate ratio (average particle diameter:lamellar thickness) of 5:1 to 25:1 and at least one of pigment selected from a group consisting of a coloring pigment, a mica pigment and a metal powder pigment, with a solution of an organic solvent containing a film-forming polymer, the thus-obtained coatings show sufficiently unique texture and soft texture, an excellent deversificative property, an excellent hiding power and free from turbidity of hues. On the basis of the finding, the present invention has been attained.